A number of different experimental approaches allow for the quantification of beta cell mass and for eventually displaying the remodeling of islets. In vitro techniques include the analysis of histological sections of pancreas by point counting morphometry and the direct measurements of islet dimensions in dissected pancreatic tissue. Ex vivo imaging techniques comprise the imaging of exteriorized pancreas by confocal microscopy or optical coherence microscopy. Finally, several non-invasive in vivo imaging techniques aim at the longitudinal quantification of total beta cell mass, i.e. magnetic resonance imaging (MRI), positron emission tomography (PET), bioluminescence imaging, or combined multimodal imaging. However, these techniques only provide indirect evidence for islet plasticity, as these various techniques do not offer the possibility to follow morphological changes in individual islets over time.